WO2013041607A1

WO2013041607A1 - Descaling device for water tank

Info

Publication number: WO2013041607A1
Application number: PCT/EP2012/068509
Authority: WO
Inventors: Lue GUO; Hua Xiao; Yi Fei ZHENG; Feng Zhou
Original assignee: Grundfos Holding A/S
Priority date: 2011-09-23
Filing date: 2012-09-20
Publication date: 2013-03-28
Also published as: CN102390884A; CN102390884B

Abstract

The present invention provides a descaling device for a water tank comprising a control circuit (100) having an anode and a cathode and a metal rod (400) disposed in the water tank, wherein the anode of the control circuit (100) is connected to the metal rod (400), and the cathode of the control circuit (100) is connected to an inner wall (500) of the water tank. The control circuit (100) further comprises: a voltage supply unit having an output port connected to the anode of the control circuit, for supplying a voltage to the metal rod (400), wherein the voltage supply unit has an enabling port; a microcontroller connected to an enabling port of the voltage supply unit, for detecting an output current of the voltage supply unit and outputting a control signal according to the detected output current so as to control the voltage supply unit. The present invention may effectively descale water tanks in view of different water qualities.

Description

DESCALI NG DEVICE FOR WATER TAN K TECHNICAL FIELD The present invention relates to a water tank, and more particularly to a descaling device for a water tank.

BACKGROUND In general, a water tank, which has a metal inner wall, of a water heater, may be heated by solar energy or in other manners. The metal inner wall may be corrupted or scale may be deposited thereto, if the water heater has been used for a long time. As a result, a life span of the water heater may be reduced while users' discomfort may be in- creased.

To solve that problem, a conventional art employs a method that a current is applied to the water tank from outside to eliminate the accumulation of the scale thereon. The principle of the method is that an anode port of a DC power supply is connected to an anode disposed in the water tank of the water heater and a cathode port of the DC power supply is connected to the metal inner wall of the water heater. When such descaling circuit operates, current may flow from the anode of the DC power supply to the metal inner wall through water to form a closed circuit, so that the metal inner wall is cathodically protected. Although the scale deposited to the wall of the metal inner wall may be eliminated by the above-mentioned method, it is impossible to detect whether the water in the water tank has been polluted or not. Therefore, even if the scale on the wall of the metal inner wall is elimi- nated, users may still feel uncomfortable. For example, if the hot water is used as drinking water, the drinking water may be the polluted water.

Moreover, if bad contact or connection exists in the descaling circuit, the descaling operation may not be performed well, and it may be difficult for the users to know whether the descaling circuit is normally operating and the users may mistakenly consider that the water tank is always descaling, thereby the life span of a water tank being shorten.

SUMMARY OF THE INVENTION

In view of the defects existing in the convention art, the present invention provides a descaling device for a water tank which can monitor the operating state of the descaling circuit in real time and turn off or turn on the descaling circuit according to the operation state of the descaling circuit.

To achieve the above object, the present invention provides a descaling device for a water tank comprising a control circuit having an anode and a cathode and a metal rod disposed in a water tank, wherein the anode of the control circuit is connected to the metal rod, and the cathode of the control circuit is connected to the inner metal wall of the water tank. The control circuit further comprises: a voltage supply unit having an output port connected to the anode of the control circuit, for supplying a voltage to the metal rod, wherein the voltage supply unit has an enabling port; a microcontroller connected to the enabling port of the voltage supply unit, for detecting an output current of the voltage supply unit and outputting a control signal according to the detected output current so as to control the voltage supply unit.

According to an embodiment of the present invention, the voltage supply unit is a voltage regulator.

According to an embodiment of the present invention, when the de- tected output current is higher than a first predetermined value, the microcontroller outputs a control signal to turn off the voltage supply unit.

According to an embodiment of the present invention, the microcon- trailer outputs an alarm signal for informing the outside of an occurrence of an error after the voltage supply unit is turned off.

According to an embodiment of the present invention, when the detected output current is zero or lower than a second predetermined value, the microcontroller outputs a prompt signal for informing the outside of an occurrence of a fault.

According to an embodiment of the present invention, the microcontroller outputs a turn-on control signal so as to restart the voltage supply unit after the fault is eliminated or the water in the water tank is changed.

According to an embodiment of the present invention, the microcontroller detects the output current of the voltage supply unit by way of a resistance feedback. According†o an embodiment of the present invention, the microcontroller further comprises a protection circuit for protecting the voltage regulator from being destroyed due to large current or electrostatics discharge and so on. Further, the protective circuit may be an LC cir- cuit.

According to an embodiment of the present invention, the micro controller is a Single-Chip Microcomputer. According to an embodiment of the present invention, the voltage regulator is one of a low dropout regulator and a three-terminal adjustable regulator with a software switch.

According to an embodiment of the present invention, the metal rod is a Ti alloy rod.

According to an embodiment of the present invention, the descaling device further comprises a consumptive metal rod disposed adjacent to the anode of the control circuit. The consumptive metal rod may be an Mg rod.

The descaling device for a water tank according to the present invention may automatically turn on or turn off the voltage supply unit according to the situation of the water quality (such as the situation of water being polluted) or the circuit fault, by using a method combining software and hardware and utilizing a character that the operating current of the control circuit varies with the water quality. Therefore, the present invention may effectively prevent the scale from being deposited on the inner wall of the water tank in view of different water quali- ties, and may also monitor the fault situation of an inner circuit thereof. The present invention may further output an alarm signal which may be displayed on a user displaying device or implemented by means of other audible and visual device according to the user's requirement. If the Mg rod is further disposed in the water tank, the present invention may prevent the Mg rod from being consumed when the control circuit operates.

BRIEF DESCIRPTION OF THE DRAWINGS

Fig.l is a schematic configuration diagram showing a descaling device for a water tank according to the present invention.

Fig.2 is a structure block of a control circuit of the descaling device for a water tank shown in Fig. l ;

Fig.3 is a structure block of the control circuit according to a first embodiment of the present invention;

Fig.4 is a structure block of the control circuit according to a second embodiment of the present invention;

Fig.5 is a structure block of the control circuit according to a third embodiment of the present invention;

Fig.6 is a circuit diagram of the control circuit according to an embodiment of the present invention.

EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limits to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout context.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limits to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," or "includes" and/or "including" or "has" and/or "having" when used herein, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, "around", "about" or "approximately" shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate; meaning that the term "around", "about" or "approximately" can be inferred if not expressly stated.

The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings in Figs. 1 - 6. In accordance with the purposes of this invention, as embodied and broadly described herein, this invention relates to a descaling device for a water tank.

Fig.l is a configuration diagram showing a descaling device for a water tank according to the present invention. As shown in Fig. l , the descaling device for a water tank according to the present invention comprises a control circuit 1 00 and a metal rod 400 which is disposed in the water tank. The control circuit 1 00 has an anode and a cathode, wherein the anode is connected to the metal rod 400 disposed in the water tank via an anode lead 200, and the cathode is connected to a metal shell 500 of the inner wall of the water tank. Thus, a closed circuit is formed among the control circuit 1 00, the metal rod 400, water and the shell 500 of the inner wall of the water tank.

The control circuit 1 00 may turn off the closed circuit according to a situation of a current flowing in the closed circuit. As shown in Fig.2, according to an embodiment of the present invention, the control circuit 1 00 comprises a voltage supply unit 1 1 0 for supplying a voltage to the metal rod 400 and a microcontroller 1 20. The output port of the voltage supply unit 1 00 is connected to the anode of the control circuit 1 00, and thus the output voltage of the voltage supply unit 1 00 is provided to the metal rod 400.

The metal rod 400 herein may be a Ti alloy rod, and also may be other rod made of metal with good conductivity, for example, Ti, P†-Ti, Ti-coa†ed copper.

The voltage supply unit 1 1 0 receives a control signal from the microcontroller 120, so that the voltage supply unit 1 1 0 is controlled to provide a voltage to the metal rod 400 according to the control signal of the microcontroller 1 20.

At the same time, the microcontroller 1 20 monitors the current situation in the closed circuit formed among the control circuit 1 00, the metal rod 400, water and the shell 500 of the water tank, namely, frequently detects the output current of the voltage supply unit 1 1 0, thereby outputting different control signals according to the obtained feedback signal related to the current situation.

Specifically, if the current flowing in the closed circuit is higher than a predetermined value (a first predetermined value) stored in the microcontroller 1 20, it is considered that the water quality may be very bad or the short circuit may occur in the anode of the control circuit, and thus the microcontroller outputs a turn-off control signal to the voltage supply unit 1 1 0 so that the voltage supply unit stops supplying a voltage to the metal rod 400. In an embodiment of the present invention, the microcontroller 120 outputs an alarm signal to the outside while outputting the turn-off control signal, so as to prompt the outside that the water in the water tank need to be changed.

On the other hand, when the microcontroller 1 20 re-detects that a feedback signal about the current is within a normal range, the microcontroller 1 20 re-enables the voltage supply unit 1 1 0. For example, in the case that the water tank is not powered off, the water in the water tank is changed, the fault of the short circuit is solved by plugging and drawing a lead, or the water quality changes to within a normal range, and so on so forth, the microcontroller 1 20 may re-detect that the feedback signal about the current is within a normal range, and then enables the voltage supply unit 1 10 to output a voltage. If the current in the closed circuit is lower than another predetermined value (a second predetermined value) stored in the microcontroller 1 20 or is zero, the microcontroller 1 20 outputs a warning signal so as to prompt an occurrence of an error. On the other hand, the microcontroller 1 20 further outputs a turn-on control signal to the voltage supply unit 1 1 0 at a certain interval while prompting the occurrence of an error, circularly detects a feedback voltage of the voltage supply unit after it is opened, and updates the prompt state according to the current state of the voltage supply unit so as to determine whether to continue prompting the occurrence of the error.

The voltage supply unit 1 1 0 may be a voltage regulator 1 1 0' that converts an input voltage from a power supply into an output voltage, and may be other circuit form that is able to provide a voltage. It should be understood for the skilled person in the art that the circuit form of the voltage supply unit 1 1 0 is a power supply device that may continuously provide the required voltage, namely, any power supply device that is able to continuously provide the voltage required by the present invention and satisfies the condition described herein is used as the voltage supply unit 1 1 0 of the present invention.

The control circuit of the present invention may further include other circuit configurations. Herein, reference is made to a voltage regulator 1 10' as the voltage supply unit 1 1 0 to elucidate the structure of the descaling device in various embodiments of the present invention. It should be understood that the structure and principle described herein may be applied to a voltage supply unit 1 1 0 in other circuit forms. As shown in Fig.3, the voltage regulator 1 10' may convert an input voltage Vin of a power supply into an appropriately voltage Vout. An output port of the voltage regulator 1 1 0' is connected to an anode of the control circuit 1 00, and thus the converted voltage Vout is supplied to the metal rod 400.

The voltage regulator 1 1 0' is a voltage regulator with a software switch. The voltage regulator 1 1 0' has an enabling port for receiving a signal from the microcontroller 1 20. Therefore, the†urn-on/†urn-off states of the voltage regulator 1 1 0' are controlled by the microcontroller 120.

The microcontroller 1 20 may detect an output current of the voltage regulator 1 10' and output a control signal according to the detected output current so as to control the voltage regulator 1 10' to be turned on or turned off.

Since the water quality in the water tank is different, the output current of the voltage regulator 1 1 0' may automatically change. For example, when the water quality is bad, i.e. the water has many impurities, the conductivity of the water is increased and thus the resistance between the metal rod 400 and the shell of the inner wall of the water tank is lowered. Therefore, the output current of the voltage regulator 1 1 0' is increased and thereby the descaling ability of the descaling device is enhanced. Moreover, if the output current of the voltage regulator 1 1 0' exceeds a certain normal range, i.e. the output current is higher than an upper limit value of the normal range, it is considered that the water in the water tank may have been polluted or be turbid due to an existence of much scale in the water tank and thus need be changed. When the microcontroller 1 20 detects that the output current of the voltage regulator 1 1 0' exceeds the normal range (i.e. is larger than the first predetermined value stored in the microcontroller 120), the microcontroller 1 20 outputs the turn-off control signal to control the voltage regulator 1 1 0' to be turned off, namely, to turn off the voltage regulator 1 1 0' .

According to another embodiment of the present invention, the microcontroller 1 20 may output an alarm signal for informing the outside of an occurrence of an error while outputting the turn-off control signal. For example, an alarm signal of informing of an occurrence of an error is outputted to a display terminal or an audible and visual alarm device which is disposed outside the water tank. The alarm manner may be various, and it should be understood for the skilled person in the art that any manner which may receive such alarm signal and perform an information in the audible and image displaying manner may be used to achieve the present invention.

According to an embodiment of the present invention, when an anode or a cathode of the control circuit 1 00 is not connected to the metal rod 400 and the shell 500 of the inner wall, or their connection faults occasionally, the output current of the voltage regulator 1 1 0' is zero or is zero occasionally. Therefore the microcontroller 1 20 may detect the change of the output current and thus output a prompt signal of informing the outside of a load being not connected to the circuit (i.e. informs of an occurrence of an error) . The prompt manner of informing of the occurrence of an error is similar to the alarm manner; therefore, the detailed description of the prompt manner will be omitted.

Here, according to an embodiment of the present invention, as shown in Fig.4, the microcontroller 120 may detect an output current of the voltage regulator 1 1 0' by way of the resistance feed- back. For example, the output current of the voltage regulator 1 10' is indirectly detected by obtaining a voltage across a resistor 1 30 connected in series with the voltage regulator 1 1 0' . The series manner between the resistor 1 30 and the voltage regulator 1 1 0' is various. For example, the resistor 1 30 may be disposed between a power supply and an input port of the voltage regulator 1 1 0' , and thus is connected in series with the voltage regulator 1 10', as long as the voltage across the resistor 1 30 can exactly reflect the output current of the voltage regulator 1 1 0' .

The voltage regulator 1 1 0' of the present invention may also be a low dropout regulator LDO or ordinary voltage regulator provided with an external switch, or may be three-terminal adjustable regulator with a software switch. The appropriate voltage regulator may be selected according to the requirement of the present invention.

The microcontroller of the present invention may be a Single-Chip Microcomputer, or may be other various programmable intelligent chips, and so on.

According to an embodiment of the present invention, the control circuit 1 00 of the present invention may further include a protection circuit 1 40 for protecting the voltage regulator. As shown in Fig.5, the protection circuit 1 40 for protecting the voltage regulator may prevent the voltage regulator 1 1 0' from being destroyed due to electrostatics discharge or interference. The circuit form of the protection circuit 1 40 for protecting the voltage regulator may be various, as long as the circuit form is able to release the static electricity when the electrostatics discharge is larger. The circuit form of the protection circuit 140, for example, may be an LC circuit.

Herein, a schematic embodiment of the descaling device accord- ing†o the present invention is described with the reference of Fig.6. The voltage regulator 110' may be an ordinary voltage regulator with a software switch, which has five ports. A port 1 may receive an input voltage from the power supply, and a port 5 may output an output voltage converted by the voltage regulator 110'. The voltage regulator 110' may further have a port 3, which is an enabling port for receiving a control signal from the microcontroller 120.

The microcontroller 120 has at least one feedback port FB and one control port EN/SHDN. The feedback port FB functions as obtaining a feedback voltage of the voltage regulator 110', and thus the microcontroller 120 may detect and judge an output current of the voltage regulator 110' according to the obtained feedback voltage. In this example, the microcontroller 120 may obtain a feedback voltage by way of a resistance feedback since the microcontroller 120 is connected in series with the resistor R130, and the feedback voltage obtained by the microcontroller 120 follows an equation: VFB=Vin-Rl 30*lout, in which VFB is a feedback voltage, Vin is a power supply voltage, and lout is an output current of the voltage regulator 110'. When the output current of the voltage regulator 110' is increased, the current flowing through the resistor R130 is increased, namely, the feedback voltage becomes small. Therefore the microcontroller 120 may judge the output current by the feedback voltage.

In this example, the power supply voltage is typically not higher than about 10V DC voltage, which is converted into about 3V by the voltage regulator 110'. Preferably, the voltage regulator 110' in this example may output a DC voltage within a range of about 0.9V to 9V, and the value of resistor R130 is selected from a range of about lohm to 50 ohms. In this example, the descaling device for a water tank according to the present invention may further include a protection circuit of the voltage regulator 1 10'. The protection circuit of the voltage regulator 1 10' may include a diode 140' and an LC circuit 150'. The voltage regulator 1 10' may be protected by the diode 140'. For example, when the voltage regulator 1 10' is turned on or turned off, a back electromotive force generated by an inductor is guided to an input port of the voltage regulator 1 10' through the diode 140' so that the voltage regulator 1 10' is protected from being impulsed by the back electromotive force. The LC circuit 150' may function as protecting the voltage regulator 1 10' from being subjected to a high-voltage impulsion due to an electrostatics discharge, and may be, for example, a LC circuit including LI, C2, and C3, as shown in Fig.6.

In this example* the descaling device for a water tank according to the present invention may further include a secondary filter circuit for filtering an output voltage of the voltage regulator 1 10'. The circuit form of the secondary filter circuit may also be an LC circuit. In an embodiment of the present invention, the LC circuit 150' including LI, C2, C3 shown in Fig.6 may be used as the secondary filter circuit.

In the circuit shown in Fig.7, when the water quality in water tank is bad, the current is increased and thus the feedback voltage VFB is reduced. Therefore, the microcontroller 120 may detect that VFB has fallen below a normal range, namely, the corresponding current is higher than an upper limit value of a normal range. For example, when the corresponding current is higher than about 150 mA, the microcontroller may output a turn-off signal to the voltage regulator 1 10' so as to control the voltage regulator 1 10' to be turned off. Herein, the microcontroller 120 may further output an alarm signal †o a display terminal or other audible and visual alarm device so as to inform the outside of the water quality becoming weak. When the circuit in the descaling device for the water tank is not in good connection, the current flowing through the resistor is zero, and thus the feedback voltage VFB is very large and is almost equal to the power supply voltage. At the time, the microcontroller 120 detects that VFB is larger than an upper limit value of a normal range and then outputs a prompt signal to the outside, so as to prompt the circuit being not connected well.

Further, the microcontroller 120 may further start the voltage regulator 110' when the circuit in the descaling device for the water tank is in good connection or the water quality becomes good. The start of the voltage regulator 110' may be automatically implemented when the circuit in the descaling device for the water tank is in good connection. After the microcontroller 120 detects an error state that the anode of the control circuit is not connected, the microcontroller 120 continually starts the voltage regulator 110' while informing of an occurrence of an error, circularly detects the feedback voltage of the voltage regulator 110' at a certain interval after the voltage regulator 110' is started, and determines whether to update the informing state according to the current state of the voltage regulator 110'. When the current exceeds an upper limit value of a normal range due to the water quality becoming bad, the microcontroller 120 may start to circularly detect a feedback voltage of the voltage regulator 110' at a certain interval after turning off the voltage regulator, and update the informing state and determine whether to enable the voltage regulator 110' according to the current state of the voltage regulator 110'.

As mentioned above, reference is made to a voltage regulator 110' as the voltage supply unit 110 to describe the present invention, but i† should be understood that the circuit structure of the above mentioned voltage regulator 1 1 0' and the principle that the microcontroller controls the voltage regulator may be applied to the control circuit 1 00 including a voltage supply unit 1 1 0 implemented in other forms.

The present invention may further provide a consumptive metal rod which is disposed adjacent to the anode of the control circuit and different from the above-mentioned metal rod. The consumptive metal rod may be an Mg rod which has active metal ions. When the control circuit operates, the Mg rod is not consumed since the above-mentioned metal rod (such as a Ti alloy rod) may generate positive ion. That is, when the power supply is applied to the control circuit, the anode of the control circuit functions as protecting the inner wall and the consumption of the Mg rod is reduced or stopped. On the contrary, when the control circuit does not operate, that is, when the power supply is not applied to the control circuit, the anode of the control circuit does not function as protecting the inner wall and the Mg rod functions as protecting the water tank by means of a natural release of the active Mg ions, thereby the double descaling operation for the water tank is realized.

While the invention has been described in connection with typical embodiments, it will be understood that the terminology used herein is illustrative and exemplary, and is not intended as limiting. Since the present invention may be implemented in various forms without departing the concept and spirit of the present invention, the embodiments mentioned above are not limited to the details set forth herein, and should be contemplated broadly according to the concept and spirit defined by the claims. Therefore, the claims intend to cover all modifications and variations which fall within the following claims and equivalents thereto.

Claims

Claims What is claimed is:

1 . A descaling device for a water tank comprising a control circuit having an anode and a cathode and a metal rod disposed in the wafer tank, wherein the anode of the control circuit is connected†o the metal rod, and the cathode of the control circuit is connected†o the inner wall of the water tank, characterized in that, the control circuit further comprises:

a voltage supply unit having an output port connected to the anode of the control circuit, for supplying a voltage to the metal rod, wherein the voltage supply unit has an enabling port;

a microcontroller connected†o the enabling port of the voltage supply unit, for defecting an output current of the voltage supply unit and outpufting a control signal according to the detected output current so as†o control the voltage supply unit.

2. The descaling device for a wafer tank of claim 1 , characterized in that, the voltage supply unit is a voltage regulator.

3. The descaling device for a wafer tank of claim 1 or 2, characterized in that, when the defected output current is higher than a first predetermined value, the microcontroller outputs a control signal†o turn off the voltage supply unit.

4. The descaling device for a wafer tank of claim 3, characterized in that, the microcontroller outputs an alarm signal for informing the outside of an occurrence of an error after the voltage supply unit is fumed off. The descaling device for a wafer fank of claim 1 or 2, characterized in that, when the defected output current is zero or lower than a second predetermined value, the microcontroller outputs a prompt signal for informing the outside of an occurrence of a fault.

The descaling device for a water fank of claim 3 or 5, characterized in that, the microcontroller outputs a turn-on control signal so as to restart the voltage supply unit after the fault is eliminated or the water in the water fank is changed.

The descaling device for a water fank of claim 6, characterized in that, the microcontroller defects the output current of the voltage supply unit by way of a resistance feedback.

The descaling device for a wafer fank of claim 2, characterized in that, the microcontroller further comprises a protection circuit for protecting the voltage regulator.

The descaling device for a water fank of claim 2, characterized in that, the voltage regulator is one of a low dropout regulator and a three-terminal adjustable regulator with a software switch.

The descaling device for a water fank of any one of claims 1 -6, characterized in that, the metal rod is a Ti alloy rod.

The descaling device for a wafer fank of any one of claims 1 -6, characterized in that, the microcontroller is a Single-Chip Microcomputer.

The descaling device for a water fank of any one of claims 1 -6, characterized in that, the descaling device further comprises a consumptive metal rod disposed adjacent to the anode of the control circuit.